The flight instructor in the amphibious, float-equipped, weight-shift-controlled trike reported that he was demonstrating multiple touch-and-go landings for the student pilot, who was in the front seat of the tandem-seat trike. He added that, during the final approach, the wind was "light and variable," and the landing was "smooth and stable." He further added that, as power was applied to takeoff, a "gust of wind and dust came in from our left and got under the wing." Subsequently, the trike veered off the runway to the right and rolled over. The wing and fuselage sustained substantial damage. The flight instructor reported that there were no preaccident mechanical malfunctions or failures with the trike that would have precluded normal operation. An automated weather observation station at the accident airport recorded that, about the time of the accident, the wind was from 330° at 9 knots. The flight instructor reported the takeoff was from runway 5.